What is the cost of switching from Photo Black to Matte Black (and vice versa), and how much time does it take?

Epson claims that switching from PK to MK uses 1.52 mL of ink and that switching from MK to PK uses 4 mL of ink. Here are the results from my own testing. Switching from PK to MK takes 2:04 minutes. According to the printer panel, 2% of MK ink is used in the process. 2% of 80 mL is 1.6 mL of ink, so this is comparable to Epson's claim of 1.52 mL. No other inks are consumed during the switch. As of October 2007, ink costs around $0.56/mL, so the cost of switching from PK to MK is about 85 cents. Switching from MK to PK takes 3:07 minutes. According to the printer panel, 5% of PK ink is used in the process. 5% of 80 mL is 4 mL of ink, so this matches Epson's claim. No other inks are consumed during the switch. As of October 2007, ink costs around $0.56/mL, so the cost of switching from MK to PK is about $2.25.  more